Briquette for the addition of tungsten to ferrous alloys



-"' Patented No November 11 1942 338 l'iolli: UllbU FICE BRIQUETTE FORTHE ADDITION OF TUNGSTEN TO FERROUS ALLOYS Arthur Linz, New York, N. Y.,assignor to Climax Molybdenum Company, New York, N. Y., a corporation ofDelaware No Drawing. Application April 22, 1941, Serial No. 389,752

6 Claims. (Cl. 75 13s The present invention relates to a novel andimproved addition agentv for the production of tungsten containingferrous alloys.

Objects and advantages of the invention will 'be set forth in parthereinafter and in part will.

be obvious herefrom, or may be learned by practice with the invention,the same being realized and attained by means of the compositions,steps,

processes and instrumentalities pointed out in be economically producedand contains a minimum of foreign material. The invention has foranother object the provision of an improved tungsten containingbriquette which can be used practically all places where other tungstenaddition agents have heretofore been used, and which is superior in onerespect or another to all of the previous tungsten addition agents.

Heretofore tungsten has been added to ferrous alloys, by a large numberof different processes involving a wide variety of different additionagents. Tungsten ores and concentrates as well as calcium tungstate havebeen proposed and used as an addition agent but have proved to be ofvery limited application due to the relatively large proportion of slagand other undesirable constituents contained therein and introducedthereby into the ferrous alloy. Tungsten trioxide, dioxide and otheroxides have all been used as addition agents, but their use has almostinvariably been attended by excessive loss of tungsten, resulting inincreased cost of producing the alloy, and furthermore their use hasbeen limited to the production of ferrous alloys to contain a smallamount of tungsten.

Ferro-tungsten has also been widely used for the production oftungsten-bearing ferrous alloys, and While there is no limit to theamount of tungsten which may be contained in the alloys producedtherewith, this type of addition agent has necessarily increased thecost due to the added operations required for the manufacture offerro-tungsten. Furthermore, ferro-tungsten has the disadvantage that itsinks to the bottom of the ladle and the resulting ferrous alloy isrendered homogeneous .only with difliculty. 55

, and calcium, requires Briquettes of tungstic oxides with carbon havebeen widely used, and while they avoid many of the disadvantages of theother alloying agents, they produce a boil, and when large percentagesof tungsten are to be added in this way, the gas evolution may beexcessive. Tungsten silicides have also been used as addition agentswhere a fairly high silicon content in the resulting alloy isunobjectionable.

In general, the various ways in which tungsten has been addedto'f'errous alloys have been substitutes for the universally usableferro-tungsten, which has its relatively high cost and its relativelyhigh specific gravity, as its principal commercial disadvantages.

In addition to the, foregoing, there have been other minor ways'proposedfor the addition of tungsten to ferrous alloys, but these have not metwith any considerable commercial use.

The present invention provides an economical tungsten addition agent'forferrous alloys, which eliminates the use of any relatively expensivereducing agents, the availability of which may be restricted, such asaluminum, silicon, magnesium a minimum of equipment for its production,eliminates the objections which have existed with respect to all of thecommercially used addition agents set forth above, and does not resultin the introduction into the molte ferrou's metal of any foreignmaterial.

Thus, the tungsten addition agent of the present invention provides auniversally acceptable tungsten containing compound for the introductionof tungsten into ferrous alloys which can be used, with considerablesavings, as a substitute for any of the tungsten addition agentsheretofore found useful, thereby simplifying th productionof tungstenaddition agents in general, as

well. as reducing the variety of such addition .agents which must becarried on hand by the manufacturer or steel maker.

In accordance with the present invention, crude tungstic oxideispartially reduced to form crude lower tungsten oxides, or crude tungstenmetal powder containing some of the lower tungsten oxides as impurities,and this oxide is mixed intimately with relatively fine powdered,granular or flake-like iron. The resultant intimate mechanical mixtureof these substances is highly compressed to form briquettes which arepreferably of uniform size. Due to the peculiar and dissimilarcharacteristics of the tungsten compound and the iron particles, noforeign binder is needed for the coherence of this mixture, and

Doom" the briquettes preferably contain not more than a trace of carbonor other impurities.

It will be understood that the foregoing general description and thefollowing detailed description as well, are exemplary and explanatorybut are not restrictive of the invention.

Referring-now in detail'to the present-preferred and illustrativeembodiments of the invention, the novel and improved tungsten containingbriquettes are formed from partially reduced crude tungstic oxide. Thetungstic oxide is reduced in a beehive or coke oven, and the re ductionis carried on until the oxide contains mostly tungsten dioxide with sometungsten oxide, and the remainder is metallic tungsten and gangue; or,the reduction may be carried on still further until the tungsten isprimarily present as metallic tungsten, with some of the other lowertungsten oxides and gangue. As used herein, the term reduced tungsticoxide refers to such a mixture comprising principally tungsten dioxide,tungsten oxide and metallic tungsten, while the terms crude tungstenpowder and "highly reduced tungstic trioxide refer to a similar mixturein which the metallic. tungsten predominates. The reducing agent mayconveniently be carbon or some other reducing agent such as pitch whichis substantially entirely removed from the tungsten compound by the endof the reduction process. than 0.25% carbon is contained in thebriquettes as they are finallymadeup. I

The reduced roasted concentrates are generally in the-form of relativelysmall particles,

the individual particles or grains having acenter which is largelytungsten dioxidesurrounded by a considerablelayer of tungsten monoxide,which in turn iscoated with the powdered me talli'c tungsten, thesesuccessive layers gradually merging into each other and being formed asthe result of a more intensive reducing action on the surface of theparticle.

The iron to be intimately mixed with the partially reduced tungstenoxides may consist of powdered granulano'rflakelike iron containing thenormal impurities, and substantial amounts of iron oxide willnotinterfere with the results to be obtained. V

Preferably the partially reduced tungsten oxides are mixed with from 7to 40 per cent of the H iron particles, although as little as 5 per centor as much as 70 per cent of the iron particles may be added to thereduced tungsten oxides. This mixture is thoroughly mixed until thetungsten containing particles and the iron particles are intimatelymixed, and the resulting mixture is briquettecl to form relatively largebriquettes which may conveniently contain a predetermined weight oftungsten. During the briquetting operation, the intimately mixedparticles of the reduced tungsten oxides and the iron particles, aresubjected to a relatively high pressure, and due to the different natureof the materials, the mixture is compressed into a relatively hard 60-herent mass which can be shipped and will stand considerable handlingwithout excessive crumbling.

In use, the briquettes may be treated in practically the same manner asis customary with ferro-tungsten. They may be added to the steel furnaceor ladle, and the tungsten is rapidly ab- Preferably, not more 7 sorbedby the melting or molten steel. The briquettes sink through the slag andvery slowly through the molten metal, the slag protecting the metallictungsten from oxidation, at the same time that it allows it to berapidly dissolved in the molten steel. Inasmuch --as the briquettes donot sink rapidly to the bottom of the ladle, the resulting alloy readilyand quickly becomes homogeneous, and no difficulty is experiencedthrough slow dispersion of the tungsten throughi cut the alloy.

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Inasmuch as the briquettes contain no foreign material, no addedimpurities are introduced into the alloy, and due to the fact that thetungsten is present in the briquettes in partly reduced form, thetungsten is put into the steel or iron with almost an absolute minimumof chemical reaction, only ferro-tungsten having a lesser chemicalreaction. Thus, the briquettes of the present invention can replace toadvantage all of the.

,1. A briqu'ette for the addition of tungsten to ferrous alloysconsisting substantially entirely of tungstic dio'xide'tungstic monoxideand metallic tungsten and iron' particles intimately mixed together andhighly compressed to form a coherent mass.

2. A briquette for the additionof tungsten to ferrous alloys consistingessentially of tungstic dioxide, tungstic monoxide and metallic tungstenin which, the metallic tungsten predominates and iron particlesintimately mixed together and highly compressed to form a coherent mass.

3. A briquette for the addition of tungsten to ferrous alloys consistingessentially of tungstic dioxide, tungstic monoxide and metallic tungstenin which the metallic tungsten predominates and iron particlesintimately mixed together.

4. A briquette'for the addition of tungsten to ferrous alloys consistingsubstantially entirely of tungstic dioxidetungstic' monoxide andmetallic tungsten and iron particles intimately 3 mixed together andhighlycompressed to form a coherent'mass and containing less'than 0.25%

carbon.

5. A briquette for the addition of tungsten t0 ferrous alloys consistingsubstantially entirely of tungstic dioxide, tungstic monoxide andmetallic tungsten and 5% to 70% iron particles intimately mixed togetherand highly compressed to form a coherent mass.

6.- A briquette for the addition of tungsten to ferrous alioysconsisting substantially entirely of tungstic dioxide, tungstic monoxideand metallic tungsten and 10% to 50% iron particles intimately mixedtogether and highly compressed to form a coherent mass.

ARTHUR LINZ.

